Thailand used evidence supplied by the National Crime Agency (NCA) to put two migrant workers on death row despite senior British officials warning that such a move could damage the reputation of UK policing, it has been revealed. In December, two Burmese labourers were convicted of the 2014 murder of backpackers David Miller and Hannah Witheridge despite the concerns of human rights groups. During their trial, the defendants claimed that they had been tortured into confessing their role in the killing.

On 15 February, an investigation by BuzzFeed News disclosed that the NCA handed over details about Mr Miller’s iPhone to Thai police. The information – the phone’s serial number – was used in the criminal trial to link Zaw Lin and Wai Phyo to the killing, as it proved that a smashed iPhone found on a property linked to the two Burmese migrants had belonged to the victim.

Government guidance suggests that law enforcement should not supply “assistance” to foreign nations that have the death penalty without written permission from ministers.